 
         items (if (= :granule concept-type)
                 (append-collection-links context items)
-                items)]
+                items)
+        ;; add relence url to header attributes if our entries have scores
+        header-attributes ATOM_HEADER_ATTRIBUTES
+        header-attributes (if (:score (first items))
+                            (merge header-attributes
+                                   {:xmlns:relevance
+                                    "http://a9.com/-/opensearch/extensions/relevance/1.0/"}))]
     (xml-fn
-      (x/element :feed ATOM_HEADER_ATTRIBUTES
+      (x/element :feed header-attributes
                  (x/element :updated {} (str (time/now)))
                  (x/element :id {} (url/atom-request-url context concept-type result-format))
                  (x/element :title {:type "text"} (concept-type->atom-title concept-type))

(defn- collection-elastic-result->query-result-item
  [elastic-result]
  (let [{concept-id :_id
         {[short-name] :short-name
          [version-id] :version-id
          [summary] :summary

        end-date (when end-date (str/replace (str end-date) #"\+0000" "Z"))
        atom-links (map #(json/decode % true) atom-links)]
    {:id concept-id
     :score score
     :title entry-title
     :short-name short-name
     :version-id version-id
